In a wideband wireless access system, a bandwidth request method is classified into a contention-based request scheme and a contention-free request scheme. In the contention-based request scheme, a plurality of users contends for a bandwidth request in one channel. In the contention-free request scheme, a bandwidth request is transmitted through a channel allocated to each user. When using the contention-free request scheme, a mobile station may transmit a bandwidth request message through a channel allocated by polling of a base station via unicast or may transmit the bandwidth request message by piggybacking on a remaining region of a previously allocated bandwidth.
FIG. 1 illustrates an uplink resource allocation procedure for a mobile station using a contention-based request scheme.
A mobile station (MS) transmits a randomly selected code division multiple access (CDMA) code to a randomly selected slot in a region allocated for a bandwidth request (S110).
Upon recognizing the CDMA code transmitted by the MS, a base station (BS) allocates a resource for the MS to transmit a bandwidth request message using a CDMA_ allocation_IE (S120). The MS then transmits the bandwidth request (BW_REQ) message using the allocated resource region (S130). The bandwidth request message includes information as to a size of a bandwidth which is being requested. If the bandwidth requested by the MS is available, the BS allocates an uplink resource (S140). The MS transmits data using the allocated uplink resource (S150).
FIG. 2 illustrates an uplink resource allocation procedure for an MS using polling in a contention-free request scheme.
A BS periodically allocates an uplink resource for the MS to transmit a bandwidth request message (S210).
The MS transmits, to the BS, the bandwidth request message including information as to a bandwidth corresponding to a size of data to be transmitted by the MS (S230).
If the bandwidth requested by the MS is available, the BS allocates an uplink resource (S240). The MS transmits corresponding data using the allocated uplink region (S250).
The conventional contention-based request scheme includes a three-step procedure (i.e., the CDMA code, allocation, and BW-REQ) and the first step may create collision. Therefore, it is not proper to transmit signaling information or traffic which is sensitive to delay. In the polling scheme, as the number of MSs receiving polling is increased, a resource for transmitting the bandwidth request message (minimum 3 bytes 8=24 bits) and signaling information for indicating the resource information are increased.